Top 10 Common Misconceptions about Earth

People believe many things which are actually not true. Here are the top ten misconceptions about Earth.

1. Great wall of China is visible from space

Reality: The Great Wall of China is frequently billed as the only man-made object visible from space, but most times, it isn’t. In fact, according to NASA, it is very difficult to see or photograph the Great Wall from low Earth orbit. It very rarely can be visible in the low orbit, and to an aided eye, under special conditions. (Source: NASA)

But, you can see a lot of things people have made, and perhaps most visible from low Earth orbit are cities at night. Cities can be seen during the day too, as can major roadways and bridges, airports, dams and reservoirs. (Source: NASA)

On 21 June 2018, ESA Astronaut Alexander Gerst wrote “I think I finally found the answer to a question I’ve been asked a 1000 times. ‘Can we see the Great Wall of China from the #ISS?’ Next to impossible with the naked eye. But I tried with an 800 mm telelens. Still tough to spot”.

The Great Wall of China. It very rarely can be visible in the Low Earth Orbit (LEO), and to an aided eye, under special conditions. It’s impossible to see it in the Medium Earth Orbit (MEO) and beyond. Photo: wikipedia

2. In the summer, the Earth is closer to the Sun, and in the winter vice versa

Reality: This is absolutely wrong. If it was true, how we could explain the fact that when it’s winter in the northern hemisphere, it’s summer in the southern hemisphere? No, the seasons exist because Earth’s axis is today tilted 23.5 degrees from the plane of its orbit around the sun. But this tilt changes. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5 degrees. Because this tilt changes, the seasons as we know them can become exaggerated. More tilt means more severe seasons – warmer summers and colder winters; less tilt means less severe seasons – cooler summers and milder winters. (Source: NASA)

Most people think the Earth’s orbit is (and in general, planets’ orbit are) strongly elliptical (another misconception which is the source of this one). No, the Earth’s orbit is (and in general, planets’ orbit are) very close to a circle. This misconception is due to orbits being shown from oblique view in most textbooks (and also in the image below) to save space.

During winter in the northern hemisphere, the Earth is tilted so that the Southern Hemisphere receives more sunlight. During summer in the Northern Hemisphere, the Northern Hemisphere gets more sunlight. Image source: Windows2Universe.org

3. Dinosaurs are extinct

Reality: Yes, most of them are extinct. But not the avian dinosaurs. Birds (Aves), also known as avian dinosaurs are still well and alive.

The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous-Tertiary (K–T) extinction which occurred approximately 66 million years ago caused extinction of all dinosaurs except for the line that had already given rise to the first birds. Based on features of the skeleton, most people studying dinosaurs consider birds to be dinosaurs. This shocking realization makes even the smallest hummingbird a legitimate dinosaur. So rather than refer to “dinosaurs” and birds as discrete, separate groups, it is best to refer to the traditional, extinct animals as “non-avian dinosaurs” and birds as, well, birds, or “avian dinosaurs.” (Source: Berkeley.edu)

Birds are “avian dinosaurs”

4. South of the Equator toilets flush and tornadoes spin in the opposite direction

Reality: No, they don’t. The Coriolis force on Earth is very weak. The Coriolis effect may play a small role in the direction of a tornado’s spin – if the circumstances are right. More often than not, however, that direction is determined by the storm system that spawned the twister in the first place. The Coriolis effect also isn’t strong enough to influence the way a normal sink drains. (Source: How Stuff Works – Science)

5. Large earthquakes increasing in frequency

Reality: Scientists have analyzed the historical record and found that the increase in seismic activity was likely due to mere chance. Peter Shearer at Scripps Institution of Oceanography and Philip Stark at the University of California, Berkeley examined the global frequency of large magnitude earthquakes from 1900 to 2011. They discovered that while the frequency of magnitude 8.0 and higher earthquakes has been slightly elevated since 2004 – at a rate of about 1.2 to 1.4 earthquakes per year – the increased rate was not statistically different from what one might expect to see from random chance. The results of the study were published on January 17, 2012 in Proceedings of the National Academy of Sciences. (Source: EarthSky.org)

6. Deserts are always hot

Reality: The driest desert on Earth is in Antarctica: McMurdo Dry Valleys. The Friis Hills in Taylor Valley, one of the McMurdo Dry Valleys haven’t seen water in 14 million years. (Source)

Deserts are also not rare, and not always sand-covered areas – other common misconceptions. About one third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or “cold deserts”.

Wright Valley, McMurdo Dry Valleys, Antarctica – from the Bull Pass. McMurdo Dry Valleys is the driest place on Earth.

7. The needle of a compass points to true north

Reality: it points to the magnetic north, or the North Magnetic Pole which moves over time due to magnetic changes in the Earth’s core. In 2001, it was determined by the Geological Survey of Canada to lie near Ellesmere Island in northern Canada at 81.3°N 110.8°W. It was situated at 83.1°N 117.8°W in 2005. In 2009, while still situated within the Canadian Arctic territorial claim at 84.9°N 131.0°W, it was moving toward Russia at between 55 and 60 kilometers (34 and 37 mi) per year. As of 2016, the pole is projected to have moved beyond the Canadian Arctic territorial claim to 86.4°N 166.3°W. (source: Wikipedia)

8. The Moon goes around the Earth in a single day

Reality: The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in approximately 27.322 days (a sidereal month). Earth and the Moon orbit about their barycentre (common center of mass), which lies about 4,600 km (2,900 mi) from Earth’s center (about 3/4 of the radius of Earth). (Source: Wikipedia)

A beautiful Earth & Moon image from NASA. This true-color image shows North and South America as they would appear from space 35,000 km (22,000 miles) above the Earth. The image is a combination of data from two satellites. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra satellite collected the land surface data over 16 days, while NOAA’s Geostationary Operational Environmental Satellite (GOES) produced a snapshot of the Earth’s clouds. Image source: NASA

9. Different countries see different phases of the Moon on the same day.

Reality: Everyone sees the same phases of the Moon. Because phases of the Moon are not caused by a shadow from the Earth (another common misconception). But people south of the equator who face North to see the Moon when it is high in the sky will see the Moon upside down so that the reverse side is lit. (Source: NASA)

10. There is a dark side of the Moon

Reality: The Moon has no side that is constantly dark; the front and back are alternately lit as the Moon rotates. Far side is a more accurate term. (Source: NASA)